Shanghai-based biopharmaceutical company Zai Lab announced on Tuesday that the sales of its drug Vyvgart has officially started in China.

Vyvgart (efgartigimod alfa injection) is used to treat generalized myasthenia gravis (gMG), a chronic autoimmune disease that causes muscle weakness. The drug was approved in China in late June.

The medicine was prescribed in Beijing, Shanghai, as well as in the provinces of Guangdong, Hubei, Henan, Jiangxi and Hebei on the same day. The China Primary Health Care Foundation, with the support of Zai Lab, also launched China's first online platform that helps gMG patients with disease management on Tuesday.

The disease gMG, which is characterized by debilitating and potentially life-threatening muscle weakness, was listed in the rare disease catalogue issued by five national ministries and commissions in China in 2018.

The disease affects skeletal muscles throughout the body, resulting in weakness and fatigue. Patients may also suffer from double vision and impediments to facial expression, speech, swallowing, and walking. In more severe cases, gMG can affect the muscles responsible for breathing.